With development of communications technologies, a Global System for Mobile Communications (Global System for Mobile Communication, GSM for short) dual card dual standby communications terminal comes into being. That is, the communications terminal can support two subscriber identity module (Subscriber Identity Module, SIM for short) cards, so that a user does not need to carry two communications terminals, and communication costs are greatly reduced. However, if two transmit timeslots of GSM overlap in the dual card dual standby communications terminal, a very large transient current may be caused, and time division duplexing (Time Division Duplexing, TDD for short) and board vibration in a dual Global System for Mobile Communications (Global System for Mobile Communication, GSM for short) project may have a risk of overrun indicators.
In the prior art, transmit powers of modems (Modem) corresponding to the two cards are separately limited, so as to avoid the risk of overrun indicators. FIG. 1 is a schematic diagram of transmit power limiting in the prior art. As shown in FIG. 1, a limiting method in the prior art specifically includes the following steps: 1) When a first demodulator (Modem1, M1 for short) performs communication by using a first maximum transmit power limit (PowerLmtMax1, PLM1 for short), a second demodulator (Modem2, M2 for short) performs access by using a second low-level transmit power limit (PowerLmtL2, PLL2 for short). 2) After the access of the M2 succeeds, a transmit power of the M1 is reduced to a first high-level transmit power limit (PowerLmtH1, PLH1 for short). 3) After the transmit power of the M1 is reduced to the PLH1, a transmit power of the M2 is increased to a second high-level transmit power limit (PowerLmtH2, PLH2 for short), so that the M1 and the M2 respectively use the PLH1 and the PLH2 to steadily limit the transmit powers. 4) After one of the modems is released, the other modem cancels the limiting and performs transmission by using a maximum transmit power. As shown in FIG. 1, if the M1 is released, the M2 performs communication by using a maximum transmit power limit second maximum transmit power limit (PowerLmtMax2, PLM2 for short).
As can be seen, in the prior art, when concurrent uplink transmission occurs, the M1 and the M2 steadily limit the transmit powers by respectively using the PLH1 and the PLH2, an equivalent total radiated power (Total Radiated Power, TRP for short) of the communications terminal is reduced, and a coverage area of a base station is reduced, resulting in degradation of communication quality of a service.